Webb telescope finds first signs of water-ice clouds on Epsilon Indi Ab
Updated
Updated · EarthSky · May 1
Webb telescope finds first signs of water-ice clouds on Epsilon Indi Ab
8 articles · Updated · EarthSky · May 1
The Max Planck Institute-led team reported the finding in The Astrophysical Journal Letters, describing the 7.6-Jupiter-mass planet 12 light-years away and orbiting its star every 180 years.
Researchers expected ammonia to dominate the upper atmosphere, but lower-than-anticipated levels pointed instead to high-altitude water-ice clouds, challenging current computer models of Jupiter-like exoplanets that often omit clouds.
The result shows Webb can probe cooler, more distant gas giants rather than mainly hot Jupiters, a step toward studying more Earth-like exoplanet atmospheres with future telescopes including NASA's Roman mission.
JWST detected water-ice clouds 12 light-years away. How does this reshape our understanding of weather on alien worlds?
Our models for giant planets were wrong. What key assumptions about Earth-like worlds might also be flawed?
JWST Detects Reflective Water-Ice Clouds on Epsilon Indi Ab, Challenging Exoplanet Atmospheric Models
Overview
In April 2026, the James Webb Space Telescope made a groundbreaking discovery by directly detecting reflective water-ice clouds in the atmosphere of Epsilon Indi Ab, a nearby cold super-Jupiter. This detection revealed an unexpected ammonia deficit, explained by ammonia condensing into ice particles within the clouds. These findings challenged existing cloud-free atmospheric models, prompting the development of more sophisticated models that include cloud physics. Epsilon Indi Ab's warmth, caused by residual heat from its formation, creates conditions that allow these clouds to form. Building on this success, astronomers are using refined techniques to study more cold giants, while the upcoming Nancy Grace Roman Space Telescope will provide complementary visible-light data, together advancing the search for life on Earth-like exoplanets.